Preparation Of Li-rich Li[Li_0.2Ni_0.2Mn_0.6]O₂Cathode Materials By A Micro Impinging Stream Reactor

In recent years, due to its low cost and high capacity (>250mAh/g), Li-rich lithium manganese material Li[Lu1-x.yMexMny]O2(Me=Co, Cr, Ni, NiCo, etc.) became a promising cathode material. Micro impinging stream reactor (MISR) is a new type of reactors, which combines micro reactor with impinging stream technology. It is a process intensification device with excellent mass transfer and heat transfer performance.In this work, a micro impinging stream reactor was adopted to prepare the Li-rich manganese cathode material Li[Li0.2Ni0.2Mn0.6]O2with excellent morphology and electrochemical performance. The optimal synthetic conditions of experiments had been obtained. On this basis, hydrothermal process was added to the experiment to further improve the morphology of samples. Finally, coating modification of the prepared materials was studied by comparing the electrochemical properties of the materials coated with3wt.%A12O3,1.5wt.%,3.0wt.%and6.0wt.%ZrO2, respectively.Results showed that the optimal experimental conditions for preparing the materials were:the ammonia concentration of0.28mol/L, stirring speed of650r/min, the reaction time for30min and cooling down in the muffle furnace after calcining at950℃in the air for20h. The prepared Li[Li0.2Ni0.2Mn0.6]O2sample was composed of spherical particles with about5μm in diameter and the surface of the sample consisted of100-200nm particles. The sample also had highly ordered layered structure. The first discharge capacity was172mAh/g and the discharge capacity increased to255mAh/g after40cycles at20mA/g (0.1C), indicating very stable cycle performance.Coated Li[Li0.2Ni0.2Mn0.6]O2(OLO) samples showed obvious coating layer. The first coulombic efficiency and discharge capacity of coated samples were improved markably. OLO sample coated with1.5wt.%ZrO2had the best electrochemical performance.